1. Field of the Disclosure
The present disclosure relates, in general, to ice making machines and, more particularly, to ice making machines using a hydrocarbon (HO) refrigerant, such as propane, and modified to use such HO refrigerant and in particular, utilizing a low refrigerant volume air condenser.
2. Discussion of the Background Art
Ice making machines are in widespread use for supplying cube ice in commercial operations. Typically, the ice making machines produce a large quantity of ice by flowing water over a large chilled surface. The chilled surface is thermally coupled to evaporator coils that are, in turn, coupled to a refrigeration system. The chilled plate, or evaporator, contains a large number of indentations on its surface where water flowing over the surface can collect. Typically, the indentations are formed recesses within a metal plate having high thermal conductivity. As water flows over the indentations, it freezes into ice.
To harvest the ice, the evaporator is heated by hot vapor flowing through the evaporator coils. The evaporator plate is warmed to a temperature sufficient to harvest the ice from the evaporator. Once freed from the evaporator surface, a large quantity of ice cubes are produced, which fall into an ice storage bin. The ice cubes produced by a typical ice making machine are square, rectangular or rhomboidal in shape and have a somewhat thin profile. Rather than having a three-dimensional cube shape, the ice cubes can be tile-shaped and have small height and width dimensions.
Typically, HFC-type refrigerants, such as R-404a are used in conventional ice making machines. R-404a is an HFC “nearly azeotropic” blend of 52 wt. % R-143a, 44 wt. % R-125, and 4 wt. % R-134a. It was designed as replacement for R-22 and R-502 CFC. Its boiling point at normal pressure is −46.5° C.; its liquid density is 0.485 g/cm3. These HFC-type refrigerants serve the useful purpose of replacing chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) which were banned from use due to environmental effects. However, HFCs are not the most environmentally friendly compounds. The use of HFC-type refrigerants are themselves falling into criticism for their environmental affects, much the same as CFCs and HCFCs were banned due to environmental impact.
In light of these shortcomings in typical prior art ice making machines, it would be useful develop an ice making machine which can use more environmentally friendly and energy efficient refrigerants. It is known that HCs, such as propane, are very environmentally friendly and efficient refrigerants. However, HCs present their own set of problems; specifically they are flammable or explosive if exposed to heat, fire or spark especially in sufficient concentrations in confined spaces. Thus, the amount of HCs which can be used as refrigerants in ice making machines should be limited to avoid disastrous results in the event of an accidental ignition or explosion. Indeed, safety agencies in the USA and Canada (such as UL and CSA) are in the early stages of approving flammable refrigerants in North America. The European safety standards, IEC standards, dealing with R-290, require that the refrigerant charge be limited to 150 grams, unless special approval is sought and received. The special approval does not apply to apparatuses the size of commercial ice making machines which are to be placed in consumer locations such as restaurants, cafeterias and the like. A need exists for such an ice making machine.
Some HCs, such as propane, do find use in commercial applications, typically in Europe, where they are often used in indirect cooling/refrigeration systems. For example, HCs may be used to cool ethylene glycol and the ethylene glycol is then transported through tubing or piping to the point where the cooling/refrigeration is effected. The actual cooling apparatus using the HC in this type of application is generally located in a ventilated isolated area, away from the area of actual cooling. Special approval is either not required or is given for these applications, due to the location of the apparatuses. If a fire or explosion occurs in this instance at the source of HC, the possibility of injury to humans is reduced. In other instances, the amount of flammable refrigerant is so minimal that the danger of fire or explosion is not a serious issue.
A need exists for an ice making machine which can use environmentally friendly HCs, but also serve in applications where consumers are close at hand, thus minimizing the possibilities of injury in the event of a fire or explosion. Preferably, in fact, the need exists for an ice making machine which can use environmentally friendly HCs yet minimizes the likelihood of fire or explosion in the first instance.
Thus, It is an object to the present disclosure to provide an ice making machine which can safely utilize HCs.
It is also an object of the present disclosure to provide an ice making machine which can utilize HCs while using an amount of HC which minimizes the risk of disastrous explosion or fire.
It is a further object of the present disclosure to provide an ice making machine which can take advantage of the efficient refrigeration properties of HCs.
It is a still further object of the present disclosure, to provide an ice making machine which matches the output of conventional machines using HFC refrigerants, but at lower energy usage.